1. Field of the Invention
The present invention relates to a film video player for generating a video signal from photographic film for display on a television monitor or receiver, and more particularly, to such a video player having means for selectively changing the magnification of the video display (zoom) and for translating the display vertically and horizontally (scan).
2. Description of the Problem
Apparatus for sensing positive or negative photographic color films to produce a video signal are well known. Telecine apparatus for producing television signals from motion picture film have been employed since the earliest days of television. The recent development of relatively low cost, reliable solid state image sensors has generated considerable interest in the development of a video player for displaying color film, such as color slides or color negatives on a home television receiver. See for example, the article in Electronics, Mar. 1, 1979, page 70 entitled "Simple Method Uses Peristaltic CCD's to Display Color Slides on TV Set".
The resolution of most popularly employed still picture photographic film formats, such as size 110, 126, 135, and disc film is substantially greater than standard television resolution, exceeding the television resolution by factors of approximately four to ten times. The full available resolutions of these film formats are not effectively used when the film image is displayed on a television set at normal magnification, i.e. where the full frame image just fills the television display.
The excess resolution available in these film formats can be employed to good effect by providing a film video player with means, such as zoom optics, for selectively changing the magnification of the displayed image. Since the magnified film image overfills the video display, it is further desirable to provide a means whereby an operator can translate (scan) the image vertically and horizontally so that any selected portion of the magnified film image can be displayed.
A film video player provided with operator controlled zoom and scan capability is very entertaining, and the visual effects achieved can be quite striking. A person using such a video player to display a favorite photograph becomes quite absorbed in exploring various portions of interest at different magnifications. Zoom and scan capability in a film video player is also usefully employed to display images such as diagrams or pages of text, where the operator may zoom in on the portions of interest.
A problem encountered with such a film video player having zoom and scan capability is that when a scan is attempted at lower magnifications, the imge may be displaced on the television display past the borders of the film frame resulting in a portion of the television display being blank. Similarly, when a peripheral portion of a magnified film frame image is being displayed, and the magnification is returned to normal, the film frame image will not be centered in the dispaly. The effect is mildly annoying, and detracts from the otherwise esthetically pleasing impact of the video display.
Another problem encountered in film video players is that the aspect ratio of a standard film format may not be identical to the aspect ratio of the television display (e.g. compare size 126 format which is square with a standard NTSC television frame which is rectangular). If the normal magnification is chosen so that the entire film frame image can be viewed at one time, there will be unsightly borders on one or two sides of the video display. Conversely, if a magnification is chosen such that the film frame just fills the video display, some of the image will lie outside the video display and will not be seen. A similar format mismatching problem arises when a rectangular format picture of substantially the same aspect ratio as the television display is taken with the camera rotated 90.degree. about its optical axis. When such a film is displayed at normal magnification, the display will be accompanied by blank borders on one or more sides.